Ohio University’s Chemistry and Biochemistry Colloquium Series presents Dr. Luis Velarde on “Unraveling the Entangled Electronic and Structural Landscape at Molecular Interfaces” on Monday, March 5, at 04:10 p.m. in Clippinger Laboratories 194.
Dr. Luis Velarde
Velarde is Assistant Professor of Chemistry at SUNY Buffalo.
The host is: Dr. Katherine Cimatu
Abstract: Understanding the delicate interplay between geometrical and electronic structure at interfaces, particularly for photoresponsive thin films and nanostructures is a challenging task of high relevance to many scientific areas such as photocatalysis, photovoltaics, and nanophotonics. We demonstrate that Doubly-Resonance Sum Frequency Generation (DR-SFG) spectroscopy can be used as a surface and species-selective probe in order to characterize how specific vibrational modes of interfacial species are coupled to excited surface electronic states and affect functional properties. We show how second-order nonlinear probes for vibronic coupling can shed light on surface aggregates in photosensitized semiconductors, structural conformers of substituted azobenzene molecules on surfaces and phonon-assisted transitions in nanostructured carbon. These studies allow us to gain insights into how specific nuclear motions may drive electronic processes at surfaces. In addition, we show how sum frequency generation vibrational spectroscopy (SFG-VS) can be used to examine the binding, orientation, and ordering of organic ligands in solution-processed nanomaterials. We present how the surface order of ionic surfactants on semiconducting single-walled carbon nanotubes is influenced by the conditions of the surrounding aqueous environment, providing new physical insights for solution-processing of carbon nanotubes in nanoelectronics. Furthermore, we present the direct relationship between surface orientation and structural motifs in thiophene- and selenophene-substituted chalcogenopyrylium (CP) dyes on gold nanoparticles as a new class of ultra-bright, NIR-absorbing Raman reporters. These results advance our understanding of the role of molecular orientation in SERS probes. The results of this work provide an opportunity for the development of controlled chemistries for the design of nanosurfaces that enable tailored properties.
Comments